In packet transmission, a packet format check process is performed after a transmission error check process at the data recipient side.
In the transmission error check process, an error is recovered by determining it as a transmission path error according to error detection (CRC (Cyclic Redundancy Check) error, parity error, for example) and performing retransmission request.
In a protocol error check process, a setting error, determination mistake and the like at the transmission source is determined according to error detection (for example, detection of an undefined packet), and the transmission is terminated by closing the port, or a retry process at a higher level layer is performed.
[Patent Document 1] Japanese Laid-open Patent Publication No. 2006-186557
[Patent Document 2] Japanese Laid-open Patent Publication No. 2006-211632
[Patent Document 3] Japanese Laid-open Patent Publication No. 2005-072950
[Patent Document 4] Japanese Laid-open Patent Publication No. 2003-264607